1. Field of the Invention
Embodiments of the invention relate to a stereoscopic image display capable of selectively implementing a two-dimensional plane image (hereinafter referred to as ‘2D image’) and a three-dimensional stereoscopic image (hereinafter referred to as ‘3D image’).
2. Discussion of the Related Art
A stereoscopic image display capable of selectively implementing a 2D image and a 3D image has been developed and has been put on the market due to the development of various contents and circuit technology. A method for implementing the 3D image of the stereoscopic image display is mainly classified into a stereoscopic technique and an autostereoscopic technique.
The stereoscopic technique, which uses a parallax image between left and right eyes of a user with a high stereoscopic effect, includes a glasses type method and a non-glasses type method, both of which have been put to practical use. In the non-glasses type method, an optical plate such as a parallax barrier for separating an optical axis of the parallax image between the left and right eyes is generally installed in front of or behind a display screen. In the glasses type method, left and right eye images each having a different polarization direction are displayed on a display panel, and a stereoscopic image is implemented using polarized glasses or liquid crystal (LC) shutter glasses.
A LC shutter glasses type stereoscopic image display alternately displays a left eye image and a right eye image on a display element every one frame and opens and closes a left eye shutter and a right eye shutter of LC shutter glasses in synchronization with a display timing, thereby implementing the 3D image. In the LC shutter glasses type stereoscopic image display, because the LC shutter glasses have a short data-on time, a luminance of the 3D image is low. Further, a 3D crosstalk is extremely generated because of the synchronization between the display element and the LC shutter glasses and the On/Off conversion response characteristic.
In a polarized glasses type stereoscopic image display, a polarization separation device, such as a patterned retarder, is attached to a display panel. The patterned retarder separates polarized light of a left eye image and a right eye image displayed on the display panel. A viewer wears polarized glasses when viewing a stereoscopic image on the polarized glasses type stereoscopic image display. Hence, the viewer sees polarized light of the left eye image through a left eye filter of the polarized glasses and polarized light of the right eye image through a right eye filter of the polarized glasses, thereby giving a stereoscopic feeling.
The display panel of the existing polarized glasses type stereoscopic image display may use a liquid crystal display panel. A parallax is generated between a pixel array of the liquid crystal display panel and the patterned retarder due to a thickness of an upper glass substrate of the liquid crystal display panel and a thickness of an upper polarizing plate, and thus leads to a poor vertical viewing angle. When the viewer views a stereoscopic image displayed on the polarized glasses type stereoscopic image display at a vertical viewing angle higher or lower than the front of the liquid crystal display panel, he or she may feel the 3D crosstalk, where the left eye image and the right eye image overlap each other, when viewing the stereoscopic image with a single eye (i.e., the left eye or the right eye).
To solve the problem of the 3D crosstalk at the vertical viewing angle in the polarized glasses type stereoscopic image display, Japanese Laid Open Publication No. 2002-185983 proposed a method for forming black stripes on a patterned retarder (or 3D film) of a stereoscopic image display. In a method different from this method, the width of black matrices formed on a liquid crystal display panel can be increased. However, the formation of the black stripes on the patterned retarder may result in a reduction in luminance of 2D and 3D images, and the black matrices may interact with the black stripes, thereby generating moiré. Further, an increase in the width of the black matrices may reduce an aperture ratio, thereby reducing the luminance of the 2D and 3D images.
To solve the problem of the polarized glasses type stereoscopic image display disclosed in Japanese Laid Open Publication No. 2002-185983, a technology for dividing each of pixels of a display panel into two parts and controlling one of the two parts using an active black stripe was disclosed in Korean Patent Application No. 10-2009-0033534 (filed on Apr. 17, 2009) and U.S. application Ser. No. 12/536,031 (filed on Aug. 5, 2009) corresponding to the present applicant, and which are hereby incorporated by reference in their entirety. The stereoscopic image display proposed by the present applicant divides each of the pixels into the two parts and writes 2D image data to each of the divided pixels in a 2D mode to thereby prevent a reduction in a luminance of a 2D image, and also displays a 3D image on the divided one part of each pixel and displays a black image on the other part in a 3D mode to thereby widen a vertical viewing angle of the 3D image. However, in the active black stripe technology, the number of gate lines was doubled because of the division of each pixel into the two parts, and thus configuration of a gate driver became complicated.